1. Field of the Invention
The present invention relates generally to a method for printing braille characters, and in particular to an improved method for printing braille characters by means of a lithographic printing process.
2. Description of the Prior Art
Braille is read by blind persons by running their fingers along the raised dots of a series of braille characters. Such persons can also write braille by means of a six-key writing machine known as a "Braillewriter" or by means of a stylus disposed on a pocket-size metal or plastic slate.
Methods for printing braille characters on various recording mediums are known in the art. See, for example, U.S. Pat. Nos. 3,132,962 and 1,936,089. Braille books are generally printed by utilizing metal press plates. The braille characters for the book are stamped on both sides of the paper utilized to fabricate the book by a method known as "interpointing". The characters are arranged so that dots impressed upon one side of a book page do not interfere with those printed on the other side of the page.
Computers have been used to increase the speed of production of braille books in recent years. In such systems, the computer converts ordinary punched cards prepared by a typist on a keypunch machine into cards punched with a braille code. A machine is then utilized to automatically produce metal plates from the braille-coded cards for printing of the braille book.
Manually-fed platen presses ae generally utilized to run the book plates. The presses are manually fed since paper for textbooks and literary books must be fed in a damp condition. The presses operate at about 3-5 second intervals, and press speed is approximately 1200-1720 sheets per hour. It is, thus, apparent that the cost and time involved in producing braille books for the blind is very great. As a result, most blind persons cannot, because of the cost of braille books, avail themselves of all the books they would like to read.